In this Reverse Shot Talkie, host Eric Hynes takes French actor-director Mathieu Amalric up to Manhattan's High Line to talk about his new film, The Blue Room (out now from Sundance Selects), which is based on the steamy 1964 crime novel by Georges Simenon. Amalric speaks frankly about the stakes involved in collaborating with wife Stéphanie Cléau on the film, in which an illicit affair leads to a very public murder trial. Not only did they cowrite the screenplay, they star opposite one another—and Cléau plays not his wife, but his mistress.

"She made this sort of joke," he recalls. "'Maybe I can be the unfaithful wife, and you can be my lover?' And I didn't find that funny at all." Yet that's exactly how Amalric eventually decided to cast the film. He goes on to talk about the perils of long-term relationships, and how hard it is to be honest about needs and desires when both parties have so much to lose. "If you say what's happening at that moment, it collapses," he says. "Sexuality is a danger, and can make everything explode." After admitting that sex can be hotter outside of a committed relationship, Amalric jokes about what he and Cléau were hoping to summon from their unique collaboration. "Maybe that's why we did the film," he says, smiling. "To get the hot back at home."